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Imaggeo on Mondays: Sneaking up from above

Imaggeo on Mondays: Sneaking up from above

Take some ice, mix in some rock, snow and maybe a little mud and the result is a rock glacier. Unlike ice glaciers (the ones we are most familiar with), rock glaciers have very little ice at the surface. Looking at today’s featured image, you’d be forgiven for thinking the Morenas Coloradas rock glacier wasn’t a glacier at all. But appearances can be misleading; as Jan Blöthe (a researcher at the University of Bonn) explains in today’s post.

The picture shows the Morenas Coloradas rock glacier, a pivotal example of actively creeping permafrost (ground that remains frozen for periods longer than two consecutive years) in the dry central Andes of Argentina. The rock glacier is located in the “Cordon del Plata” range, some 50 km east of the city of Mendoza.

The rock glacier fills the entire valley and slowly creeps downslope creating impressive lobes and tongues with steep fronts. With more than 4 km length, the Morenas Coloradas is one of the largest rock glaciers of the central Andes.

Taken from a drone, the picture looks straight up the rock glacier into the main amphitheatre-like valley formed by glacial erosion located at ~4500 m.a.s.l. From there, large amounts of loose debris are moved down the valley at speeds on the order of a few meters per year. The creeping process forms tongues of material that override each other, producing the characteristic surface with steps, ridges and furrows.

The central Andes of Argentina are semi-arid, receiving less than 500 mm of precipitation per year, mainly falling as snow during the winter. The region is famous for its wines, which are grow in the dry Andean foreland that is heavily dependent on meltwater from the mountains. How much of this meltwater is actually stored in ice-rich permafrost landforms is unknown.

As opposed to ice glaciers, rock glaciers show a delayed reaction to a changing climate, as large amounts of debris cover the ground ice, isolating it from rising air temperatures. With large areas located above the lower altitudinal limit of mountain permafrost of ~3600 m.a.s.l., the central Andes of Argentina might store significant amounts of water in the subsurface.

Using mainly near-surface geophysics, our research tries to quantify the water storage capacities in the very abundant and impressive rock glaciers of the region. The Morenas Coloradas rock glacier is of special importance in this regard, as first geophysical measurements date back to the 1980s. Since then, active layer thickness has dramatically increased in the lower parts of the rock glacier, indicating that also the ground ice of the permafrost domain of the central Andes is suffering under the currently warming climate.

A final remark: Thanks goes to the entire team of this research project, namely Christian Halla, Estefania Bottegal, Joachim Götz, Lothar Schrott, Dario Trombotto, Floreana Miesen, Lorenz Banzer, Julius Isigkeit, Henning Clemens, and Thorsten Höser.

By Jan Blöthe, University of Bonn, Germany

Imaggeo on Mondays: Flying Rocks

Imaggeo on Mondays:  Flying Rocks

The picture was taken at a hillslope close to the glacier tongue of the Great Aletsch Glacier, the largest glacier in the Alps. With a length of 23 km it is located in the eastern Bernese Alps of Switzerland and composed of the three smaller glaciers Aletschfirn, Jungfraufirn and Eternal snow field converging at Concordia where the ice thickness was measured to be around 900m. The whole area was declared a UNESCO World Heritage site in 2001.

Alpine slopes in the region have been exposed to cycles of glacial erosion and retreat and have responded to changing slope geometry and changing stress conditions. This may have induced fracturing of the rock faces, which in turn, can be the cause of slow moving landslides and more catastrophic rock-face collapse events.

The group of engineering geology of Prof. Dr. Simon Loew of ETH Zurich is conducting research just around the strongly retreating glacier tongue of the Great Aletsch Glacier (more than 30 m length change in 2014). Together with geodesists (i.a. Stefan Conzett in the picture) extensive field work has been carried out, from 2013 to 2015, around the surroundings of the glacier tongue. This project has two main goals: (1) monitor and analyze recent rock slope instabilities surrounding the glacier tongue and currently showing movements of up to 4 cm / hour and (2) monitor cyclic deformation of the valley slopes caused by changing groundwater level, changing temperatures and glacial meltwater variations in the ice next to the slope.

Today’s image was taken by Franziska Glueer, a PhD student at ETH Zürich, during the installation of reflector prisms (which allows for the accurate calculation of position) in the steep rock walls which will be precisely measured by a total station.

The whole monitoring setup consists of 2 total stations (which send out a beam to the reflector prisms, allowing the measurement of distance, horizontal and vertical angle) on each side of the glacier, with more than 70 reflectors being monitored hourly, several permanent gps-stations taking constantly positioning data and meteo-sensors, which keep track of changing temperature and weather conditions, registering data every 30 min.

By Franziska Glueer, a PhD student at ETH Zürich

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Imaggeo on Mondays: Annapurna snow avalanche

Imaggeo on Mondays: Annapurna snow avalanche

The Annapurna massif is located in an imposing 55 km long collection of peaks in the Himalayas, which behave as a single structural block. Composed of one peak (Annapurna I Main) in excess of 8000 m, a further thirteen peaks over 7000 m and sixteen more of over 6000 m, the massif forms a striking structure within the Himalayas.

Annapurna I Main, the tenth highest peak in the world, is towering at an impressive 8,091 m. Renowned for its difficult climbing conditions, it holds one of the highest fatality rates of the 8000+ peaks. October 2014 marked a particular dark period in the mountain’s climbing history when 39 trekkers were killed during severe snowstorms and avalanches while completing a popular hike circling Annapurna I.

Martin Struck, a PhD student at the University of Wollongong, Australia, captured this extraordinary photograph of a surging avalanche early one morning in October 2012. Martin visited the Annapurna massif as part of his Diploma project at the University of Potsdam about suspended sediment fluxes in the Kali Gandaki River which cuts the world’s deepest gorge through the Himalayas between the Annapurna and Dhaulagiri massifs. The snow avalanche careered down the ~35° sloping northeast flank of Tilicho himal, a peak only 10 km away from the Annapurna I summit.

“The avalanche is one of five I spotted that morning in the area. The tracks and runout zones of previous snow and/or dry snow avalanches are clearly visible in the image,” describes Martin.

He explains that rising morning temperatures triggered the avalanches, causing the failure of stable snow which had fallen on the night before.

The area is close to Tilicho Lake, located at about 4900 m above sea level, and one of many Himalayan glacial lakes which play a crucial role in the supply of water to the inhabitants of Nepal.

“Snow and glacial melt contribute approximately 10% to the annual discharge of the main Nepalese rivers, but are of significant important outside the monsoon season,” explains Martin.

Earlier on this year, a study published in the open access journal, The Cryosphere, found that if greenhouse-gas emissions continue to rise, glaciers in the Everest region of the Himalayas could experience dramatic change in the decades to come. The glacier model used in the paper shows that glacier volume could be reduced between 70% and 99% by 2100. The findings have important implications for the future availability of water in the region: a significant decrease in glacial volume would have consequences for agriculture and hydropower generation. You can learn more about this research and it’s consequences in this Press Release: Glacier changes at the top of the world – Over 70% of glacier volume in Everest region could be lost by 2100.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Trapped air

Can you imagine walking into the depths of an icy, white, long and cavernous channel within a thick glacier? That is exactly what Kay Helfricht did in 2012 to obtain this week’s Imaggeo on Mondays photograph.

Tellbreen Glacier is a small glacier (3.5Km long) in the vicinity of the Longyearbyen valley in the Svalbard region of Norway. Despite its limited size, it is an important glacier. One of the key parameters scientist use to understand how glaciers are affect by a warming climate is how the melt water is transported through to the front of the glacier. The majority of models utilise data from temperate or polythermal glaciers, i.e., glaciers which have free water within the icy matrix. Tellbreen is a cold glacier, meaning the basal layers of ice are frozen to the glacier bed; despite the traditional view that cold glaciers are not able to store, transport and release water, Baelun and Benn, 2011 found Tellbreen does this year round.

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Kay visited Tellbreen whilst at the Artic Glaciology course at the University Centre in Svalbard. ‘Each weak one excursion led us to glaciers in the vicinity of Longyearbyen’ says Kay, ‘this day we visited the glacier Tellbreen. Near the tongue of the glacier the outlet of an englacial channel enabled us to explore the inside of the glacier. We went for some tens of meters into the channel.’

What the group found were that the walls of ice either side of the channel contained impurities, from stones to gravel, as well as mud and also water. The image above shows ‘air trapped in the ice-walls of the conduit at a time when the conduit would have been filled with meltwater of the glacier’ explains Kay. Air accumulated in bubbles at the roof of the conduit. When the water in the conduit started to refreeze along the side-walls, these smooth lenticular bubbles were trapped and stored in the ice. Studying the bubbles and other impurities in the ice can give hints on the history of the glaciers ice flow and its thermal regime over several decades.

References

Baelum. K., Benn. D.I.: Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar, The Cyosphere, 5, 139-149, 2011

Naegeli. K., Lovell. H., Zemp. M., Benn, I. The hydrological system of Tellbreen, a cold-based valley glacier on Svalbard, investigated by using a systematic glacio-speleologicalapproach, Geophysical Research Abstracts, 16, EGU2014-6149, 2014 (conference abstract)

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

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